a. Field of the Invention
The instant invention relates generally to medical imaging and navigation and more particularly to a system and method for compensation of motion in a moving organ using an internal reference sensor.
b. Background Art
Systems and methods for obtaining and displaying two-dimensional and three-dimensional images are known in the art, for example, as seen by reference to U.S. Pat. No. 7,386,339 entitled “MEDICAL IMAGING AND NAVIGATION SYSTEM” to Strommer et al., hereby incorporated by reference in its entirety. Strommer et al. disclose a medical imaging and navigation system that has a capability for constructing and displaying three-dimensional images of moving organs, synchronously with the actual movement of these organs and synchronously with an invasive surgical tool, such as a catheter. The system includes a medical positioning system (MPS) for ascertaining the location and orientation of multiple MPS sensors, a two-dimensional imaging system having an image detector for obtaining two-dimensional images of the moving organ and a superimposing processor. The MPS system includes a sensor mounted on the surgical tool and a sensor attached to the body of the patient for a positional reference (“Patient Reference Sensor”, or PRS). The system acquires a plurality of two-dimensional images (and respective location/orientation data and organ timing data, e.g., ECG signal) and records the sets of positions and orientation of all sensors. The system reconstructs a three-dimensional image from the combination of 2-D images and sensor data. When a physician inserts the surgical tool into the body of the patient, the system also detects the location and orientation of the MPS sensor that is mounted on the tool. The superimposing processor super-imposes a representation of the surgical tool on the currently displayed two-dimensional and three-dimensional images, which may be played back in accordance with real-time ECG data.
The PRS is provided so that the sensors associated with the surgical tools remain in a co-registered coordinate system to the X-ray imager at all times. The system detects movements of the patient using the PRS (e.g., patient body movements and respiration induced movements). The movements (as sensed by the PRS) are used to shift the coordinate system relative to the coordinate system in which the two-dimensional images were acquired. Therefore, in Strommer et al., the projection of real-time location information on previously recorded 2-D or 3-D images is both ECG synchronized and respiration compensated. However, in some situations, there is little or no correlation between the external motion compensation signals being used (i.e., the ECG signal and the PRS readings) and the internal motion of a region of interest. For example only, in the case of atrial fibrillation, the ECG signal may not effectively serve as a predictor or correlation input for the motion of the atria.
There is therefore a need for a system and method for compensation for the motion of a moving organ that minimizes or eliminates one or more of the problems set forth above.